External combustion rotary engine

ABSTRACT

An external combustion rotary engine includes a piston arranged to travel around a toroidal chamber in an engine block. Intake and exhaust ports extend into the chamber at radially separated positions. A gate hinged at a top edge extend across the chamber between the intake and exhaust ports. A driveshaft is aligned with the center of the toroidal chamber, and a tubular cam is coaxially and slidably positioned on the driveshaft within the engine block. The cam includes a protruding cam surface with a spiral leading edge. The piston is attached to the edge of a disc concentric with and attached to the driveshaft. The cam is slidable along the driveshaft for advancing or retracting the spiral leading edge from an intake valve for varying the timing thereof. When the valve is opened, the piston is pushed around the chamber by a pressurized gas introduced through the intake port. Exhaust gas is pushed ahead of the piston through the exhaust port. The gate is opened when struck by the piston. After the piston has traveled past the gate, the gate is closed, and the cycle is repeated.

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

This invention relates generally to rotary engines.

2. Prior Art:

An external combustion rotary engine is disclosed in my U.S. Pat. No.4,076,471. It includes a plurality of pistons each traveling around atoroidal chamber. Each piston is attached to the edge of a discconcentric with the center of the chamber. The disc is attached around adriveshaft. A normally-closed gate with two spring-loaded pivotingmembers is arranged within each chamber. An intake port is positioned onone side of the gate, and an exhaust port is positioned on the otherside of the gate. The gate is arranged for opening only in the directionof the intake port. An intake valve is controlled by an overhead camarranged on a camshaft, which is driven by a belt connected to thedriveshaft. A pressurized gas produced by external combustion, such assteam, is directed into the chamber through the intake port. The pistonis driven around the chamber by the gas pushing against it, and thedriveshaft is caused to rotate by the disc fixedly connected between thepiston and the driveshaft. Gas on the front side of the piston is pushedout the exhaust port. The gate is opened when struck by the piston.After the piston has traveled past the gate, the gate is closed, and thecycle is repeated.

OBJECTS OF THE INVENTION

An object of the present invention is to provide an improved externalcombustion rotary engine.

Another object of the present invention is to provide a rotary enginewith simpler gates that also provide an improved seal.

Another object of the present invention is to provide a rotary enginewith pistons that provide an improved seal.

Another object of the present invention is to provide a rotary enginewith an internal cam for simplicity and compactness.

Another object of the present invention is to provide a rotary enginewith a cam arranged for providing throttle control.

Another object of the present invention is to provide a rotary enginethat provides the longest heatstroke possible.

Yet another object of the present invention is to provide a rotaryengine that converts the kinetic energy of a gas into rotary motion withmaximum efficiency.

Further objects of the present invention will become apparent from aconsideration of the drawings and ensuing description.

BRIEF SUMMARY OF THE INVENTION

An external combustion rotary engine comprises a plurality of pistonseach arranged to travel around a separate toroidal chamber in an engineblock. Intake and exhaust ports communicate with the chamber at radiallyseparated positions. A normally-closed gate hinged at a top edge extendacross the chamber between the intake and exhaust ports. A driveshaft isaligned with the center of the toroidal chamber, and a cam is coaxiallyand slidably positioned on the driveshaft within the engine block. Thepiston is attached to the edge of a disc concentric with and attached tothe driveshaft. The cam includes a protruding cam surface with a spiralleading edge. The cam is slidable along the driveshaft for advancing orretracting the spiral leading edge from the stem of an intake valve forvarying the timing thereof. When the valve is opened, the piston ispushed around the chamber by a pressurized gas introduced through theintake port. Exhaust gas is pushed ahead of the piston through theexhaust port. The gate is opened when struck by the piston. After thepiston has traveled past the gate, the gate is closed, and the cycle isrepeated.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a side perspective view of an external combustion rotaryengine in accordance with the invention.

FIG. 2 is a side sectional view of the engine, taken along line 2--2 inFIG. 1.

FIG. 3 is a side view of a piston and a disc of the engine.

FIG. 4 is an edge-on view of the piston and the disc.

FIG. 5 is a side view of a cam of the engine.

FIG. 6 is an end sectional view of the cam taken along line 6--6 in FIG.5.

FIG. 7 is an end sectional view of the engine, taken along line 7--7 inFIG. 2.

FIG. 8 is an end sectional view of the engine, taken along line 8--8 inFIG. 2.

FIG. 9 is an exploded side view of a gate and its pivot.

FIG. 10 is an exploded end view of the gate and pivot.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-2:

In accordance with a preferred embodiment of the invention shown in theside perspective view of FIG. 1, an external combustion rotary engineincludes an engine block with a mid block 10 bolted between end blocks11 and 12. An intake plenum 13 with a threaded hole 15 is attached tothe top of mid block 10, and exhaust connectors 14 are attached to thetop of end blocks 11 and 12. A driveshaft 16 extends from end block 11.

The engine is shown in a sectional view in FIG. 2. A pair of toroidalchambers 17 are arranged between end block 11 and mid block 10, andbetween end block 12 and mid block 10. The center of each chamber 17 isaligned with driveshaft 16. A pair discs 18 are positioned between endblock 11 and mid block 10, and between end block 12 and mid block 10.Each disc 18 has a diameter equal to the inside diameter of chamber 17.Disc 18 is fixedly and concentrically attached to driveshaft 16 forsimultaneous rotation. A sealing ring 19 is attached to the edge of disc18 for providing a gas seal between chamber 17 and disc 18. An annularseal 20 is arranged around driveshaft 16 on the side of end block 11.

An intake port 21 extends between chamber 17 and intake plenum 13 on midblock 10. The top of an intake valve 22 is positioned over the top ofintake port 21. Valve 22 is biased downwardly by a spring 23 positionedbetween its top and a bracket 24 attached to mid block 10. An exhaustport 25 extends between chamber 17 and exhaust connector 14 on endblocks 11 and 12. Intake port 21 and exhaust port 25 are radially offsetalong the periphery of chamber 17. A normally-closed gate 26 extendsacross chamber 17 to form a barrier between intake port 21 and exhaustport 25. Gate 26 is slightly wider and taller than most of chamber 17,which includes a slightly wider portion for receiving gate 26. Gate 26is hinged at its top edge about a pivot 27, which is loaded by a coilspring 28 for biasing downwardly against disc 18. Coil spring 28 isconcentric about the axis of pivot 27. Coil spring 28 has an inner endattached to pivot 27, and an outer end anchored by a pin 52. Coil spring28 is retained in a hole 53 by a plug 54.

A tubular cam 29 is positioned in a cam chamber 30 in mid block 10, andis coaxially positioned around driveshaft 16. Cam 29 is rotationallylocked to driveshaft 16 for simultaneous rotation by a pin 31 extendingthrough a hole (FIG. 5) in cam 29, a slot 32 in driveshaft 16, and ahole in a rod 33 coaxially positioned within driveshaft 16. Cam 29 androd 33 are thus connected by pin 31 for simultaneous sliding movementalong driveshaft 16. Slot 32 in driveshaft 16 enables pin 31 to slidewith cam 29. Rod 33 is biased toward end block 12 by a spring 34, sothat cam 29 is also biased in the same direction. A coaxial plunger 35can be moved in or out of driveshaft 16 by a throttle lever 36 connectedthereto and pivoted about a post 37 attached to end block 12. Plunger 35is biased outwardly by a spring 38. A connection between rotating rod 33and non-rotating plunger 35 is provided by a ball 39 positionedtherebetween. Cam 29 includes protruding cam surfaces 40 engaging thestems of intake valves 22. Cam 29 is completely internal of the engineblock, and is driven directly by driveshaft 16 without a belt, so thatthe engine is simpler and more compact.

When the top of throttle lever 36 is pivoted away from the engine block,plunger 35 is moved inwardly, cam 29 is moved toward end block 11, andthe stems of intake valves 22 are caused to ride up to the top of camsurfaces 40, as shown in FIG. 2, so that intake valves 22 are opened.When the top of throttle lever 36 is pivoted toward the engine block,plunger 35 is moved outwardly, cam 29 is moved toward end block 12, andcam surfaces 40 are disengaged from the stems of intake valves 22, sothat intake valves 22 are closed. Throttle control is thus provided bymoving lever 36.

FIGS. 3-4:

One of discs 18 is shown in a side view in FIG. 3 and an edge-on view inFIG. 4. A key notch 41 on a driveshaft mounting hole 42 is provided formating with a corresponding key tab (not shown) on driveshaft 16 (FIG.2). A piston 43 made of polytetrafluoroethylene, sold under thetrademark TEFLON, is attached to the edge of disc 18. In the view shown,piston 43 is arranged for clockwise rotation. Piston 43 includes a frontside which is slanted backwardly, and which includes a slightly convexcontour. A metal support 44 extends between a hollow interior of piston43 and a matching notch 45 extending into the edge of disc 18. Support44 is locked in notch 45 by a key 46. The ends of sealing ring 19 arebent inwardly against the front and back sides of support 44. A springloaded tensioning member 47 extending from a hole in disc 18 engages oneend of ring 19 to tighten it against the edge of disc 18.

FIGS. 5-6:

Cam 29 is shown in a side view in FIG. 5 and in an end sectional view inFIG. 6. Cam 29 includes protruding cam surfaces 40 which are offset by180 degrees. Each cam surface 40 includes a spiral leading edge 48 and anotch 49. The lift for intake valves 22 (FIG. 2) is determined by spiralleading edge 48. If cam 29 is fully advanced, such as the position shownin FIG. 2, the valves are lifted or opened for almost the entirerevolution of cam 29, except for a few degrees when notch 49 is passedunder the valves. The few degrees of closing is timed to coincide withthe passage of piston 43 (FIG. 3) through gate 26 (FIG. 2), when gate 26is opened. If cam 29 is partially advanced, spiral leading edge 48 willdisengage from the intake valve for a greater number of degrees orportion of the cam's revolution, so that the intake valve will be closedfor a longer time. Thus variable valve timing and throttle control areprovided by controlling the advance of spiral leading edge 48 relativeto the intake valve. Holes 50 are for passing pin 31 (FIG. 2).

FIGS. 7-8:

Mid block 10 is shown in an end sectional view in FIG. 7. A pressurizedgas G is fed into chamber 17 through intake port 21. Gas G may be anysuitable pressurized gas, such as steam, an aerosol propellant,compressed air, etc. Piston 43 is pushed around chamber 17 by the forceof gas G against the back side thereof. Piston 43 forms a lever ormoment arm of a fixed length relative to the center of driveshaft 16, sothat the kinetic energy of gas G is converted into rotary motion withmaximum efficiency. At full throttle, intake valve 22 is opened foralmost the entire revolution of piston 43 so as to provide the longestpossible heat stroke. Being made of polytetrafluoroethylene, piston 43slides around chamber 17 with minimal friction, while it provides animproved seal. Gate 26, which is arranged for opening only in thedirection of gas flow or piston rotation, is kept closed against theedge of disc 18 by spring and gas pressure. Gate 26 is simpler andprovides an improved seal.

End block 11 is shown in an end sectional view in FIG. 8. Piston 43 isshown in the same position as it is in FIG. 7. Exhaust gas E is pushedout exhaust port 25 by the front side of piston 43. Gate 26 is pivotedupwardly against a recess 51 when struck by piston 43. Shock to gate 26is minimized by the convex front side of piston 43. During the brieftime when gate 26 is opened, intake valve 22 (FIG. 2) is closed, evenduring full throttle. When piston 43 is past, gate 26 is biased to theclosed position by spring pressure, and the intake valve is opened againto begin another cycle. The other disc and piston are offset by 180degrees for balance.

FIGS. 9-10:

Gate 26 and its pivot 27 are shown in an exploded side view in FIG. 9and an end view in FIG. 10. Gate 26 includes a cylindrical head 55 and aconstricted neck 56 for sliding into a slot 57 of tubular pivot 27.

SUMMARY AND SCOPE

Accordingly, I have provided an improved external combustion rotaryengine. It includes simpler gates that provide an improved seal. Itincludes pistons that also provide an improved seal. It includes compactinternal cams for actuating intake valves, and the cams are arranged forproviding throttle control. It provides the longest possible heatstroke,and it converts the kinetic energy of a gas into rotary motion withmaximum efficiency.

Although the above descriptions are specific, they should not beconsidered as limitations on the scope of the invention, but only asexamples of the embodiments. Many substitutes and variations arepossible within the teachings of the invention. For example, instead ofrectangular, the cross section of toroidal chamber 17 may be of othershapes, such as square or circular. More or fewer chambers may beprovided. Plunger 35 and ball 39 may be eliminated, and rod 33 may beextended to engage lever 36; the tip of rod 33 may engage lever 36without being attached thereto, so that rod 33 is free to rotate againstlever 36. Rod 33, ball 39, and plunger 35 may be eliminated, and cam 29may be extended out of end block 12 for directly engaging lever 36.Instead of pin 31 and slot 32, a rib may be arranged along driveshaft16, and a slot may be arranged on the inside of cam 29 for engaging therib, so that cam 29 is locked to driveshaft 16 for simultaneousrotation, but is free to slide along thereon. Therefore, the scope ofthe invention should be determined by the appended claims and theirlegal equivalents, not by the examples given.

I claim:
 1. A rotary engine, comprising:a toroidal chamber having anouter circumference and an inner circumference concentric about an axis;an intake port extending into said toroidal chamber for introducing apressurized gas; an exhaust port extending from said toroidal chamberadjacent said intake port for venting an exhaust gas; a gate extendingacross said toroidal chamber between said intake port and said exhaustport, an outer edge of said gate hinged about a pivot parallel to saidaxis and outside said outer circumference of said toroidal chamber, saidgate being biased to a closed position across said toroidal chamber,said gate being arranged to open only in one direction toward saidintake port, said pivot includes a tube with a longitudinal slot, andsaid gate includes a cylindrical head and a constricted neck, saidcylindrical head sliding into said tube, said constricted neck slidinginto said longitudinal slot; and a piston positioned within saidtoroidal chamber, a back of said piston for being acted upon by saidpressurized gas, so that said piston is driven around said toroidalchamber in said direction, said gate being normally-closed for directingsaid pressurized gas to flow in said direction, a front of said pistonpushing said exhaust gas out through said exhaust port, said gatepivoting open when struck by said piston to allow passage of saidpiston, said gate being biased closed after said piston has passed.
 2. Arotary engine, comprising:a toroidal chamber having an outercircumference and an inner circumference concentric about an axis; anintake port extending into said toroidal chamber for introducing apressurized gas; an exhaust port extending from said toroidal chamberadjacent said intake port for venting an exhaust gas; a gate extendingacross said toroidal chamber between said intake port and said exhaustport, an outer edge of said gate hinged about a pivot parallel to saidaxis and outside said outer circumference of said toroidal chamber, saidgate being biased to a closed position across said toroidal chamber,said gate being arranged to open only in one direction toward saidintake port; said pivot includes a tube with a longitudinal slot, andsaid gate includes a cylindrical head and a constricted neck, saidcylindrical head sliding into said tube, said constricted neck slidinginto said longitudinal slot; a piston positioned within said toroidalchamber, a back of said piston for being acted upon by said pressurizedgas, so that said piston is driven around said toroidal chamber in saiddirection, said gate being normally-closed for directing saidpressurized gas to flow in said direction, a front of said pistonpushing said exhaust gas out through said exhaust port, said gatepivoting open when struck by said piston to allow passage of saidpiston, said gate being biased closed after said piston has passed; adriveshaft aligned with said axis of said toroidal chamber, saiddriveshaft connected to said piston for simultaneous rotation; a tubularcam coaxially positioned on said driveshaft and arranged forsimultaneous rotation; and an intake valve positioned over said intakeport, said intake valve having a stem with a tip engaging said cam, saidstem following a protruding cam surface of said cam as said cam rotates,so as to control opening and closing of said intake valve on said intakeport.